In the synthetic polymer industry, it is well known to contact a solution of polymer with hot water and steam to form a slurry of polymer particles in water and a vapour stream comprising the solvent from the polymer solution and water vapour. The aforesaid vapour steam is processed so as to recover the solvent. The slurry of polymer particles in water is treated so as to grossly separate the polymer particles from the water and the separated polymer particles are then dried to yield essentially water free polymer. The water recovered from the separation of the polymer particles from the water may be partly recycled back to the stage at which the solution of polymer is contacted with hot water and steam or to the stage at which the polymer particles are grossly separated from the water--see U.S. Pat. Nos. 3,131,160 and 3,590,026. The slurry of polymer particles in water consists of polymer particles of a wide range of size including some small (fine) particles known in the business as fines. At the stage where the polymer particles are grossly separated from the water, it is well known that small (fine) polymer particles are carried with the water. The separation of the polymer particles from the water is not able to retain all of these small polymer particles with the majority of the larger polymer particles and the small polymer particles tend to be carried away with the water. This water stream containing the small polymer particles has to be treated to recover the small polymer particles, such as by treatment with, for example, hydrophic organic amines to cause agglomeration of the fine particles so that the so-agglomerated particles can be separated, as described in U.S. Pat. No. 3,160,586, or by decanting means and/or by using dissolved air flotation equipment, so that the water stream can then be properly treated to reduce dissolved inorganic components to make it suitable for re-use or discharge.